1. Field of the Invention
The present invention relates to an ink ribbon cartridge which is used in a printer apparatus, in which a cartridge main body with an ink ribbon housed therein is mounted and a color material of the ink ribbon is then transferred to an image printing medium by a thermal head. More specifically, the present invention relates to an ink ribbon cartridge, in which a large amount of ink ribbon can be wound.
2. Description of the Related Art
As a printer apparatus which prints an image or a character on an image printing medium, there is a printer apparatus which prints a color image or a character by transferring a color material, which forms an ink layer provided on one side face of an ink ribbon, to an image printing medium. This printer apparatus is provided with a thermal head which transfers the color material of the ink ribbon to the image printing medium, and a platen which is provided at a position which faces the thermal head, and supports the ink ribbon and the image printing medium. This printer apparatus transfers the color material of the ink ribbon to the image printing medium by superposing the ink ribbon on the image printing medium between the thermal head and the platen and applying heat energy to the ink ribbon by the thermal head. In this way, the printer apparatus prints a color image or character.
The ink ribbon which is used in such a thermal transfer type printer apparatus is usually housed in a wound state in an ink ribbon cartridge. The ink ribbon cartridge has a supply spool and a winding spool, on which the ink ribbon is wound, and these spools are housed in a supply-side ribbon housing section and a winding-side ribbon housing section, which are provided in a cartridge main body, so as to be able to rotate. When the ink ribbon cartridge is mounted on a mounting section of the printer apparatus, the spools are rotated, so that the ink ribbon is drawn out from the supply spool. The ink ribbon travels along with the image printing medium between the thermal head and the platen, thereby being served for printing, and then, is wound on the winding spool.
But, in order to improve convenience of such a printer apparatus, it is preferable to increase the amount, that is, the number of windings, of the ink ribbon which is housed in the ink ribbon cartridge, so as to be able to print more images. On the other hand, considering compatibility with an existing printer apparatus, it is not possible to increase without limitation the size of the ink ribbon cartridge. It is necessary to make the ink ribbon cartridge a size allowing it to be mounted on a cartridge mounting section of an existing printer apparatus even with the number of windings of the ink ribbon increased. Therefore, in order to increase the number of windings of the ink ribbon while making the ink ribbon cartridge to have a size capable of be mounted on a cartridge mounting section of an existing printer apparatus, it is necessary to increase the number of windings of the ink ribbon without changing an outer shape or a size as far as possible.
In order to realize this, it is necessary to increase the volumes of the supply-side ribbon housing section and the winding-side ribbon housing section by making the thickness of the shell constituting the cartridge main body to be thin. However, if the shell constituting the cartridge main body is made to be thin in thickness, strength of the cartridge main body is reduced.
For example, a pair of shells, which is butted to each other so as to constitute the cartridge main body, is provided at butting end portions with staggered engagement pieces in order to prevent the butted shells from being out of alignment. If the shells are made to be thin in thickness, in accordance with this, the engagement pieces are made to be thin, and strength is also reduced. Therefore, when the engagement pieces are made to be thin, workability at the time when constituting the cartridge main body by butting a pair of shells is also reduced.
Also, if a pair of shells, which constitute the cartridge main body, are made to be thin in thickness, strength of the cartridge main body is reduced, so that the ribbon cartridge is bent and deformed by tension of the ink ribbon at the time of transport of the ink ribbon during image printing operation or the like. In that case, there is a fear that wrinkles or the like may occur in the ink ribbon which is sent from the supply spool. Also, there is a fear that the ink ribbon is wound on the winding spool with a bias to one side.
Also, in general, the supply spool and the winding spool are housed in the supply-side ribbon housing section and the winding-side ribbon housing section of the cartridge main body so as to have a certain degree of rattling and be able to rotate. The rattling is provided so as to make the driving shaft of the printer apparatus be smoothly engaged with a driving hole formed in one end portion of the spool. On the other hand, in order to prevent the ink ribbon wound on each spool from coming into contact with the inner face of each ribbon housing section, it is necessary to make each ribbon housing section be larger than a maximum winding diameter of each spool. That is, it is necessary to make each ribbon housing section be large in consideration of the rattling amount of the spool. In that case, the ink ribbon cartridge becomes too large, so that the cartridge may not be mounted on the mounting section of an existing printer apparatus.
An example of the above-described related art is disclosed in Japanese Unexamined Patent Application Publication No. 2007-230158.